The present invention relates to packaged semiconductor devices and to methods for packaging, and particularly to resin-encapsulated and fully insulated packages for discrete or integrated devices.
The basic requirements in packaging semiconductor devices are to provide environmental protection, while also providing wiring from the semiconductor chip to external connections. A vast variety of approaches have been proposed for this.
Among the many fully insulated device packages previously proposed is the ISOWATT-218 package, generally shown in FIG. 1, and various similar packages. These include ISOWATT-220 packages, as well as ISOWATT-221 and others. See the SGS-Thompson databooks on POWER BIPOLAR TRANSISTORS (1. ed. 1989), and SCRs AND TRISCS (2nd ed. 1991), both of which are hereby incorporated by reference. This type of package has a through-hole tab which can be used to achieve good thermal conductivity (by bolting this tab to a heat sink). The disclosed innovations will be described with specific reference to this type of package, but are not strictly limited to such packages.
A problem encountered in the manufacture of semiconductor devices encapsulated in resin and electrically insulated is ensuring a satisfactory level of quality and reliability of the electrical insulation provided by the package. Problems may be manifested in the following drawbacks:
the high pressure with which the resin is injected in the die during the transfer molding process, PA1 the possibility of detachment or resin breakage under the metal plate which supports the semiconductor chip, PA1 the considerable risk of defects in the resin near pins which ensure plate positioning during the transfer molding process, and PA1 the possibility of defective horizontal positioning of the metal plate in the die during the transfer molding process.
The disclosed inventions advantageously provide an electrically insulated plastic device completely surrounded by resin which is obtainable by a more tolerant manufacturing process than in the prior art.
A further advantage is a process for manufacturing defect-free plastic devices with a high level of reliability without increasing manufacturing costs.
The semiconductor device in the present invention comprises a resin enclosure and a metal plate surrounded by the enclosure. Onto this plate is brazed a semiconductor chip, on one end of which there is an external connector and on the other end a through hole. This through hole allows the attachment of the device to an external support and/or heat sink. Preferably the plate outline has on a second side, opposite that which leads to the connector, an opening. This opening, in its innermost part, radiuses with said hole in the plate; and this recess displays an extension mouth not smaller than the diameter of said hole. The plate has on the two remaining sides additional lateral indentations extending for at least one third of their length, and the plate surface opposite the side that supports the semiconductor chip has a step transition between first and second planar portions.
Other inventive solutions are indicated in the claims set forth below.